In the description to follow it is important that a clear distinction be made between solutions entering and leaving various components. Therefore, adopted herein is the notation of the standard setting body on absorption systems in the U.S., the ASHRAE Technical Committee (8.3) on absorption machines. Their notation is given in the following quote from the ASHRAE 1979 Equipment Hand Book, Chapter 14:
"To avoid confusion of terminology in the absorption field, ASHRAE Technical Committee (8.3) recommends that the following standarized terms for the absorbent-refrigerant solution. Weak absorbent is that solution which has picked up refrigerant in the absorber and is then weak in its affinity for refrigerant. Strong absorbent is that solution which has had refrigerant driven from it in the generator and, therefore has a strong affinity for refrigerant".
In the past, many inventions have been made in the field of absorption refrigeration/heat pump system. A thoroughly comprehensive discussion of the problems and prior art activities is presented in U.S. Pat. No. 4,441,332 W. H. Wilkinson. The disclosure of that patent is included herein by reference and this invention relates to improvements in that system.
Another prior art patent of interest to the background of this invention is U.S. Pat. No. 4,424,688 W. H. Wilkinson. That patent relates to a power unit as defined therein, for an absorption heat exchange system wherein the refrigerant/absorbent solution is progressively desorbed in stages and then condensed. It provides for increased efficiency in the desorption process, by means of a maximized heat exchange system configuration.
Other patents in this general field include U.S. Pat. No. 3,495,420 Loweth et al. which shows the typical unit in which the refrigerant/absorbent solution pair is subjected to heat by the application of heat to the bottom and sides of a reservoir container.
As explained in the Wilkinson patent-"332", the invention to which this application is directed is termed a four chamber system. Two chambers are operatively connected to one two chamber subsystem and two other chambers are operatively connected to another two chamber subsystem. One subsystem employs a higher temperature solution pair having good higher temperature performance, preferably lithium-bromide/water, with water as a refrigerant and lithium-bromide as the absorbent. The other subsystem employs a different solution pair, preferably ammonia/water with ammonia as the refrigerant and water as the absorbent.
The first mentioned subsystem is operated at a higher temperature, and the system configuration allows the selected pair to avoid freezing and crystalization problems. The other second subsystem employs a lower temperature pair having good low temperature performance properties and is operated at lower temperatures in the range where an organic would be expected to operate successfully without toxicity, corrosion or stability problems and where temperatures below freezing are acceptable. In the prior patent, the first subsystem and the second subsystem; i.e. higher temperature and lower temperature subsystem respectfully, are operatively combined and connected by placing the higher temperature condenser in heat exchange relationship with the lower temperature desorber, with other components of the total system also arranged in specified combinations.
In the disclosure to follow of this invention, the first subsystem may be interchangeably termed the high subsystem and the second the low subsystem. Components of each may be termed in the same manner, respectively.